Recombinant Ixodes scapularis Calreticulin Binds Complement Proteins but Does Not Protect Borrelia burgdorferi from Complement Killing

• DOI: 10.3390/pathogens13070560
• Publication Date: 2024-07-03T12:45:34Z
• Authors: Moiz Ashraf Ansari; Thu-Thuy Nguyen; Klaudia Izabela K...; William Tae Heung...; Tae Kwon Kim; Albert Mulenga
• Keywords: Ixodes scapularis; C3-convertase

Ixodes scapularis is a blood-feeding obligate ectoparasite responsible for transmitting the Lyme disease (LD) agent, Borrelia burgdorferi. During feeding process, I. injects B. burgdorferi into host along with its saliva, facilitating transmission and colonization of LD agent. Tick calreticulin (CRT) one earliest tick saliva proteins identified currently utilized as biomarker bites. Our recent findings revealed elevated levels CRT in proteome burgdorferi-infected nymphs compared to uninfected ticks. Differential precipitation (DiffPOP) LC-MS/MS analyses were used identify interactions between Ixs (I. scapularis) human plasma further explore potential role shielding from complement killing. We observed that although yeast-expressed recombinant (r) IxsCRT binds C1 complex (C1q, C1r, C1s), activator via classical cascade, it did not inhibit deposition membrane attack (MAC) pathway. Intriguingly, rIxsCRT intermediate (C3, C5, C9) reduces MAC through lectin Despite inhibition pathway, protect serum-sensitive strain (B314/pBBE22Luc) complement-induced As establishes local dermal infection before disseminating secondary organs, noteworthy promotes replication culture. hypothesize may contribute and/or by acting decoy fostering at site.